Storage-battery-testing instrument



*.l. W. FITZ GERALD.

STORAGE BATTERY TESTING TNSTRUMENT.

APPLICATION FILED MAR '26, i920 PIGHIQIINOV., I5, Im.

s@ /YLWmJI/fm KUHN W. FTZG L'I.

i D, OF DETROIT, MCmG-ill.

STORAGE-BATTERYTEST1NG INSTRUMENT.

Specication of Letters Fatent.

ratentea new.. it, aaai.

Application. led March 26, i920. Serial No. 368,998.

To all whom "it may concern Be it known that l, JOHN W. FrrzGnnALn, a citizen ot' the United States of America, residing at Detroit, in the county oilVayne and State of lllichigan, have invented certain new and useful Improvements in Storage-Battery-'lesting Instruments, of which the following is a specification, reference being had therein to the accompanying drawings.

ln the present state of the art it is usual to test storage batteries by the specific gravity or' the electrolyte. This requires the use of a hydronieter and the Withdrawal of a` sufiicient quantity of the electrolyte from the battery jar to float the same. lt frequently happens that the battery to be tested is low in electrolyte so that the requisite quantity cannot be Withdrawn and Where Water is first added, the reading Will not be correct unless time is tirst given for proper diti'usion.V

When the current is drawn from a storage battery, the tall in voltage is proportional to the stored charge, but the variation is so slight that an ordinaryv volt meter'would scarcely indicate the same. rlhe construction of a` suiiiciently sensitive instrument would be costly and would involve diculties in the use of the same so that the hydrometer test is preferable. 'lo secure a simple and Sensitive indicator, l have devised a construction in which a standard current volume is drawn from the battery, regardless of the charge therein, by suitably adjusting the resistance in the circuit and the amount of adjustment in the resistance is measured to indicate the stored charge in the battery. Preferably, the adjustment for changing the resistance is indicated on a scalev calibrated either in units ot charge of any specific gravity of the electrolyte, or any other indication which would show the condition of the battery.

lJarious specific constructions may be used to embody the principle of my invention, but as shown,-

Figure l is a longitudinal section through one torni of instrument;

Fig. 2 is a horizontal section there through;

Fig. Bis a plan View;

Fig. Ll is a diagram illustrating the electrical connections.

A are pointed prods or electrodes for establishing connection with the storage bettery by pressing the same into the soft metal terminals thereof. B is a casing on which said prods are mounted, and C is a handle projecting upward from the casing and torming a means for pressing the prods into engagement with the terminals. As indicated in the diagram of Fig. 4, the prods A are connected into an electrical circuit, including a rheostat D and an electromagnet E, the latter being arranged to operate a circuit closer F, which is so adjusted that it will be actuated only when a. predetermined current volume flows through the circuit. The rheostat D is provided with an adjustable contact G by which the resistance can be cut in or cut out, and H is an index hand connected with the contact Gr and operating in connection with a scale l. Preferably, the adjustable contact G is operated by the same handle C, which is used for pressing the prods into engagement with the terminals, said handle being revolubly mounted in the casing B and connected to both the contact G and the index l-l. lhe circuit closer F is connected into an independent electrical circuit in multiple with the circuit through the rheostat and magnet. and this independent circuit preferably contains a lamp bulb J or other indicator.

lilith the construction as described, to test the battery the prods A are pressed into the terminals by the handle C and the latter is then turned slowly in a direction to cut out resistance in the rheostat and when the resistance is sufficiently lowered, so that the current flowing through the magnet E is of a predetermined volume, the circuit closer F will be operated, which illuminating the lamp l will at once attract the attention ot the operator. The reading is then talren of the position off the index H upon the scale l and this will indicate the condition ot charge in the battery. Preferably, the lamp il is so arranged that it will illuminate the scale, so that it is possible to test the battery in the darle.

ln the construction of the instrument, l preferably use a high resistance conductor tor forming hothY the convolutions oit the magnet E and the rheostat D. its' shown, the rheostat is formed by a circuler scent of the conductor `with which the contact il" is engaged and the scale l is upon a segment ot the same angular magnitude. rThe electromagnet E and circuit closer F may be of standard construction, such as used many places in the art and the Whole instrument is therefore one simple in construction and inexpensive to manufacture.

That I claim as my invention is:

l. A storage battery tester, comprising means for closing an electrical circuit between the terminals of the battery, an adjustable member for varying the resistance of said circuit, and means cooperating with said adjustable member for indicating the battery charge by the position of the adjustable member.

2. A storage battery tester, comprising means for closing an electrical circuit between the terminals of the battery, an adjustable member for varying the resistance of said circuit, means in said circuit for indicating the flow therethrough ot' a predetermined current volume, and means cooperating with said adjustable member for indicating by the position thercot' when said predetermined current volume is attained the amount ot' charge in the battery.

A storage battery tester, comprising means for closing an electrical circuit between the battery terminals, a rheostat included in said circuit, a movablecontact member for Varying the resistance of said rheostat, an electromagnet in said circuit, indicator means actuated by said magnet upon the flow through said circuit of a predetermined current volume, and means cooperating with said movable contact for indicating by the position thereof the charge in the battery.

4. A storage battery tester, comprising a pair of prods for effecting electrical connection with the terminals of the battery, a handle for pressing said prods into tbe terminals, an electric circuit between said prods including a rheostat and a current volume indicator, an adjustable contact with said rheostat, and means cooperating with said adjustable contact for indicating by the position thereof the charge in the battery.

5. A storage battery tester, comprising a pair ot prods, a frame on which said prods are mounted, a handle rotativcly engaging said frame and forming a means for pressing the prods into contact with the battery terminals, an electric circuit between said prods, a rheostat and an indicator for a predetermined current volume included in said JOHN W. FITZGERALD. 

